The present technology relates to an electrophoresis device including migrating particles and a porous layer, a method of manufacturing the electrophoresis device, a display including the electrophoresis device, a display substrate including the electrophoresis device, and an electronic unit including the display and the display substrate.
Recently, a display, which exhibits high image quality at low power consumption, has been increasingly demanded with spread of a variety of electronic units such as a mobile phone and a personal digital assistant (PDA). In particular, attention is currently focused on an electronic book terminal to read character information for a long time, along with start of electronic book distribution service. It is therefore desirable to provide a display having a display grade suitable for such an application.
A cholesteric liquid crystal type, an electrophoresis type, an electrochromic type, a twist-ball type, and the like have been proposed as a display method of the display for reading. In particular, a reflection type is preferable since the reflection type uses reflection (scattering) of outside light for bright display as in paper, resulting in a display grade similar to a display grade of paper. In addition, the reflection type needs no backlight, leading to a reduction in power consumption.
An electrophoresis-type display, which uses an electrophoretic phenomenon to produce light-and-darkness (contrast), is a potential candidate of the reflection-type display since the electrophoresis-type display exhibits high-speed response at low power consumption. Thus, various investigations have been made on a display principle of the electrophoresis-type display.
In detail, a technique has been proposed, in which two types of charged particles, having different optical reflection characteristics and different polarities, are dispersed in an insulative liquid, and each type of charged particles are transferred using such a difference in polarity (for example, see Japanese Examined Patent Application Publication No. 50-015115 and Japanese Patent No. 4188091). In this technique, distribution of the two types of charged particles varies depending on electric fields, resulting in production of contrast based on a difference in optical reflection characteristics.
Another technique has been proposed, in which charged particles are dispersed in an insulative liquid, and a porous layer having different optical reflection characteristics from those of the charged particles is used to transfer the charged particles through pores in the porous layer (for example, see Japanese Unexamined Patent Application Publication Nos. 2005-107146, 2005-128143, and 2002-244163 and Japanese Examined Patent Application Publication No. 50-015120). The porous layer may be a polymer film having laser-drilled pores, a woven cloth of a synthetic fiber, an open-cell porous polymer, and/or the like, for example. In this technique, distribution of the charged particles varies depending on electric fields, resulting in production of contrast based on the difference in optical reflection characteristics.
In addition, there have been proposed a technique of enclosing charged particles in microcapsules, and a technique of using a dividing wall structure to partition a space in which charged particles are allowed to exist (for example, see Japanese Patent No. 2551783 and Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-526817). Aggregation, precipitation, and convection of the charged particles are suppressed through the techniques.